The ladder logic cross reference tool is without a doubt the feature I use most.
Back in the day if you wanted to run a cross-reference on tags you had to go through an actual paper printout made from a dot matrix printer. The cross-reference print out could fill an entire box. I would grab post it notes and mark the various places the bit was used. What a nightmare.
Thankfully technology has changed PLC’s for the better. Now cross-referencing is done with the click of a button. All instances are displayed and hyper linked.
To use the cross-reference tool simply right click a tag, routine, or module.
Select Go To Cross Reference from the pop up window. Alternatively you can use the quick key combination “CTL-E”. A cross reference window will appear displaying all instances of the tag, routine, or module.
The window displays the element (instruction) that reference the data, the exact location such as program, routine, and rung number, as well as other information. All instances are hyperlinked; double clicking a row will navigate your software to the instance used in the ladder logic. If you have navigated to the ladder logic and would like to return to the cross reference window use the hot key combination “CTL-TAB “or from the Windows Menu (Top of the Screen) select Cross Reference.
The cross reference operation is an indispensable tool you can use to quickly navigate to every place an element is used in an application.
As an example lets pretend you are an engineer working hard writing code for some clandestine operation. You get a call from maintenance claiming your code has reprogrammed its self. I’m not kidding this happens, well kind of. After some troubleshooting you trace the problem to a faulty input on an IO Module. You need to get the Clod-Hopper-Infuser machine back up and running quickly, so you make an executive decision and land the input wire on a different input. Just one problem, the project is big, really big, the input could be used many times. Luckily you know how to use the cross-reference tool, so you do it, and find the input is used 12 times in 4 different programs. A simple cross reference, address replacement and just like that the Clod-Hopper-Infuser is back up and doing whatever it does.